If you are using live LIST, missing dimensions will immediately prompt a pop-up alerting you and allowing you to provide the dimensions. Make sure you use inches and pounds for measurements/dimensions (e.g.1, 2, 1.5, or 0.25 (leading zero for partial lbs or inches).

ScanPower automatically sends a dimension-only feed and sets the item aside while we wait for Amazon to process it.  This usually takes 5-15 minutes.

Once the dimensions have been accepted by Amazon the item will appear READY below the shipment grid.

If you are using Batch (Private) Listing and attempt to add at item to a batch (either manually, or importing a spreadsheet or buylist), you will be notified of the missing dimensions and the item will not be added to the batch. 

To add the dimensions and fix the issue, you will need to use the live LIST function as described above.